This research deals with semilunar valves of the body, including the aortic valve and venous valves. Objectives of the research are to harmonize modern discoveries of valve structure at the tissue and cellular level with currently developing views of valve function, and thus to aid in the surgical correction or replacement of diseased valves. Other objectives are to produce insights into valve diseases by disrupting normal structure and function, and to determine how tissue turnover relates to the maintenance of normal or the development of abnormal conditions. Viewing valve structure from a functional perspective, we will examine the orientation and component parts of valvular connective tissues with respect to the stresses they receive, alter parts of valves to unbalance the stresses and observe the consequences to tissue orientation and composition, and determine how tissue metabolism reflected in turnover of components reacts to normal or unbalanced stresses. Conversely, clarifying structural features should assist with functional studies, suggesting where markers to demonstrate function ought to be placed, where tests of stress may show particular strengths and weaknesses of tissues, and perhaps how abnormal functions may be produced by selectively damaging structural components. To accomplish the research objectives, tissue histology and ultrastructure of normal and abnormal valves will be examined. We will look particularly for features to explain such functions as contracture of valve leaflets, flexibility of tissues, and aberrant growth in response to unusual stress or trauma. We will study valves from animals, which can be readily obtained and experimentally manipulated, and compare them when feasible or necessary with valves from human autopsies. We will also use radioautography to investigate the turnover of tissues in animal valves, radioactively labeled to mark the sites of new tissue synthesis.